Recycling of waste materials is highly desirable from many viewpoints, not the least of which are financial and ecological. Properly sorted recyclable materials can often be sold for significant revenue. Many of the more valuable recyclable materials do not biodegrade within a short period, and so their recycling significantly reduces the strain on local landfills and ultimately the environment.
Typically, waste streams are composed of a variety of types of waste materials. One such waste stream is generated from the recovery and recycling of automobiles or other large machinery and appliances. For examples, at the end of its useful life, an automobile is shredded. This shredded material is processed to recover ferrous and non-ferrous metals. The remaining materials, referred to as automobile shredder residue (ASR), which may still include ferrous and non-ferrous metals, including copper wire and other recyclable materials, is typically disposed of in a landfill. Recently, efforts have been made to further recover materials, such as non-ferrous metals including copper from copper wiring and plastics. Similar efforts have been made to recover materials from whitegood shredder residue (WSR), which are the waste materials left over after recovering ferrous metals from shredded machinery or large appliances. Other waste streams that have recoverable materials may include electronic components (also known as “e-waste” or “waste electrical and electronic equipment (WEEE)), building components, retrieved landfill material, or other industrial waste streams. However, in many instances, no cost-effective methods are available to effectively sort waste materials that contain diverse materials. This deficiency has been particularly true for non-ferrous materials, and particularly for non-metallic materials, such as non-ferrous metals, including copper wiring. For example, one approach to recycling wiring has been to station a number of laborers along a sorting line, each of whom manually sorts through shredded waste and manually selects the desired recyclables from the sorting line. This approach is not sustainable in most economics since the labor component is too high.
While some aspects of ferrous and non-ferrous recycling has been automated for some time, mainly through the use of magnets, eddy current separators, induction sensors and density separators, these techniques are ineffective for sorting some non-ferrous metals, such as copper wire. Again, labor-intensive manual processing has been employed to recover wiring and other non-ferrous metal materials. Because of the cost of labor, many of these manual processes are conducted in other countries and transporting the materials adds to the cost.
Many processes for identifying and separating materials are know in the art. For example, some processes are disclosed in U.S. Patent Application Publication 2007/0187299, entitled “Dissimilar materials sorting process, system and apparata,” and U.S. Patent Application Publication 2008/0257794, entitled “Method and system for sorting and processing recycled materials.” The entire content of these patent application publications are incorporated herein by reference. However, not all processes are efficient for recovering non-ferrous metals and the sequencing of these processes is one factor in developing a cost-effective recovery process. Also, many processes are “wet,” that is, they involve using water or other liquid media. Wet processes tend to be less cost effective, in part, because of the extra processing required to manage and dry materials and these processes often produce waste sludge that must be managed. Further, these processes may still provide a waste stream that can be further refined to provide a recovered product that has a high concentration of copper and other valuable metals.
In view of the foregoing, a need exists for cost-effective, efficient methods and systems for recovering materials from a waste stream, such as materials seen in a recycling process, including non-ferrous metals, in a manner that facilitates revenue recovery while also reducing landfill and, preferably using a dry process, where the process results in a high concentration of recovered metals.